French patents 2 036 890, 2 366 835 and 2 647 343 describe pharmaceutical forms which are characterized in that they dissolve or disintegrate rapidly in an aqueous medium or in saliva.
However, said patents are not appropriate for handling plants or, in particular, for obtaining plant-based compositions in the solid form which have an enhanced absorption and result in a distinctly improved bioavailability of the active principles. In fact, the chemical composition of the active principles of a plant and/or part of a plant is very complex; the basic molecules, namely heteroside genins, terpene and tri-terpene derivatives, alkaloids, phenolic products, various volatile products, etc., are present in association with other molecules, in particular sugars, giving them very different molecular weights ranging from 100-200 to several thousand daltons; these heterosides are very sensitive to degradation, both during the preparation of the composition, due to the different treatments which they can undergo, and during their administration.
European patent application 0 420 729 describes a preparative technique resulting in the stabilization of fresh or dry whole plants and/or parts of plants, or of their extracts, which makes it possible to obtain the totum of the stabilized starting plant material in a form which is stable in a liquid medium, principally an alcoholic medium.
Said European patent application 0 420 729 also describes the preparation of a solid composition by a physical operation or absorption on a support. However, such a solid composition has a number of disadvantages:
the percentage of support must be markedly greater than that of the plant suspension in order effectively to have an absorption capacity, PA1 the resulting solid composition contains solvents which are incompatible with conversion of this composition to a porous galenic form (especially lyophilizate), and PA1 the plants' active principles of the solid forms described in said patent application do not have an optimal bioavailability. PA1 (A) one or more of the plants' active principles included in a homogeneous suspension of fresh or dry plants obtained by (a) cleaning and/or drying of the plant or part of the plant, (b) cryocomminution at a temperature below 0.degree. C. until a particle size of less than about 100 .mu.m is obtained, (c) immersion of the particles for a suitable time in at least one appropriate solvent, (d) separation of the liquid phase and the solid phase of the suspension obtained, (e) expression of the solid phase obtained in (d) by cold pressing, and (f) mixing of the liquid phase obtained in (d) and the expressed liquid obtained in (e), and PA1 (B) at least one absorption promoter with a sequestering action, PA1 a solid composition I such as defined above (dried mixture of (A)+(B)), and PA1 (C) at least one absorption promoter selected from surfactants.
It was therefore of particular interest to be able to provide a dry galenic form based on plants, which is stable and permits the absorption of all the active principles, without degradation of the latter, especially at the moment of absorption (improvement of the bioavailability).